The formation of life is an intricate and fascinating mystery. Although we have several hypotheses for how inert molecules could have turned into living organisms, we're still unsure what exactly happened. One suggestion proposes that the key factors are hydrothermal vents, fissures from the ocean floor from which heated water comes forth.

Researchers have now attempted to reproduce in the lab the complex chemistry that takes place around these vents. The team used mixtures that are supposed to mimic the composition of the ancient Earth's ocean. Just like in real life, the lab vents gave the system crucial chemical energy that led to the formation of amino acids, the building blocks of proteins. The new study is published in the journal Proceedings of the National Academy of Sciences.

"Understanding how far you can go with just organics and minerals before you have an actual cell is really important for understanding what types of environments life could emerge from," lead author Dr Laurie Barge, from the Jet Propulsion Laboratory, said in a statement. "Also, investigating how things like the atmosphere, the ocean and the minerals in the vents all impact this can help you understand how likely this is to have occurred on another planet."

Their primordial ocean cocktail was a mixture of water, minerals, and molecules such as pyruvate and ammonia, which are needed as precursors to amino acids and were abundant in the early Earth. The solution was heated to 70°C (158°F) – a likely temperature around vents – and its pH was adjusted to mimic an alkaline environment. They also added “green rust”, the common term for iron hydroxide, which was common on our young planet.

A time-lapse video of a miniature hydrothermal chimney forming in the lab, as it would in early Earth's ocean. NASA/JPL-Caltech/Flores

The team saw the formation of the amino acid alanine and the alpha hydroxy acid lactate as soon as small quantities of oxygen were introduced. Oxygen is not something the primordial Earth was rich in.

"We've shown that in geological conditions similar to early Earth, and maybe to other planets, we can form amino acids and alpha hydroxy acids from a simple reaction under mild conditions that would have existed on the seafloor," explained Barge.

This work is part of nine years' worth of studies about the energy and the chemicals released from these geological features. Earth is not alone in having vents. Saturn’s moon Enceladus has them and Jupiter’s moon Europa might have them too. Having hydrothermal vents doesn’t equate to life, but this work provides new insight into what kinds of chemistry (and maybe even organisms) we might find elsewhere in the cosmos.